The present invention relates to a system and a process for treating and purifying high strength wastewater for recycling or discharge to groundwater sources.
In many parts of the country, the available supply of fresh groundwater has been drastically lowered due to extended periods of drought. In some areas, groundwater has become polluted by solid waste materials, toxic chemicals, industrial waste and the like. The demand for clean groundwater has caused municipalities to investigate ways to treat and purify wastewater.
A number of different wastewater treatment and water purification methods and systems are known in the art. For example, U.S. Pat. No. 4,415,450 to Wolverton illustrates a method for treating wastewater which comprises the steps of subjecting the wastewater to an anaerobic settling step for at least six hours and passing the liquid effluent from the anaerobic settling step through a filter cell in an upflow manner wherein the effluent is subjected first to the action of an anaerobic and facultative microorganism and then to the action of aerobic microorganisms and the roots of at least one vascular aquatic plant. The system employed by Wolverton comprises a preliminary vessel in which is carried anaerobic settling and a hybrid filter for the effluent from the preliminary vessel. The hybrid filter has a lower portion inoculated on the surface with anaerobic and facultative microorganisms and an upper portion inoculated on the surface with aerobic microorganisms and which is growing vascular aquatic plants.
U.S. Pat. No. 4,793,929 to Kickuth exemplifies another method for purifying sewage waters. In this method, the sewage water is caused to react with atmospheric oxygen to oxidize ammonia in the sewage water to nitrate in a first purification stage. In a second subsequent purification stage, which contains areas rich in atmospheric oxygen and areas poor in atmospheric oxygen, the nitrate formed in the first purification stage is converted to nitrogen.
U.S. Pat. No. 4,333,837 to Plosz et al. illustrates a process for purifying water that is polluted with diffuse substances such as fertilizers, mineral and soil particles, oils, wastes, detergents and primarily inorganic substances which might accelerate undesirable entrophication of the receiving waters. The process comprises the steps of introducing the polluted water into a defined area such as a basin; spreading the water crosswise to increase its surface area; and extracting the diffuse pollutants by applying a biological treatment by the expedient of at least one group of suitable aquatic plants. The apparatus for performing the process comprises means that provide a flow path for the water; at least one dividing structure that performs the spreading; and at least one aquatic plant region, with at least one plant zone, wherein the plants contribute to the biological treatment.
U.S. Pat. No. 5,078,882 to Northrop relates to a bioconversion reactor and system that has utility in the treatment of wastewater. When used to treat wastewater, the wastewater influent passes through a preliminary screen where grit and other large particulate matter are removed for direct cycling to a solids ecoreactor. Thereafter, the preliminary cleaned influent enters the bioreactor. The bioreactor comprises a structurally contained and physically controlled microbial growth zone. Its principal function is to attach soluble materials to living aggregates of biomass and to begin the bioconversion process through the association of the undesirable material with microbial physiological processes. The bioreactor may contain multiple different subenvironments including aerobic, anoxic, and/or anaerobic zones, mixing, quiescent, settling and solids separation zones and one or more recycles. The effluent from the bioreactor, and any solids which may be wasted separately from the effluent, are cycled into the solids ecoreactor which is preferably located directly on top of the georeactor. The solids ecoreactor contains maximally diversified populations of plants, animals, and microorganisms, all living in an extensive variety of different subenvironments.
U.S. Pat. No. 5,137,625 to Wolverton illustrates still another water purification system. The system shown in this patent comprises a multi-stage active biological wastewater treatment apparatus. The apparatus contains an anaerobic, sludge settling first lagoon. A controlled flow aspirator system then injects air into the odoriferous effluent from the anaerobic chamber as part of the natural water flow out of the chamber into the first of a series of biological treatment chambers. The first treatment chambers use duckweed. A harvesting apparatus is provided to retain the growing biomass of duckweed that occurs as a result of the treatment process. Within the aerobic duckweed treatment chambers, a rotating effluent outflow pipe retains an effective biomass of duckweed for the treatment process and removes a chosen quantity of the growing biomass for harvesting. A final treatment stage uses high density grasses to form a filter mat and produce the high surface area needed for enhance bacterial action. The final treated effluent is then partially diverted and recirculated, being sprayed to form an upper layer of substantially pure, fecal coliform free, oxygenated water, covering the anaerobic waste water within the initial anaerobic chamber, eliminating the release of odors.
Published European patent application 0 390 265 to Bonaventura illustrates a process for purifying wastewater that comprises oxidation of the wastewaters with oxygen in the presence of a catalyst; phytopurification by causing the wastewaters to flow through one or more cells inside which plants are contained; and filtration of the wastewater in the presence of zeolite.
While these processes are capable of purifying wastewaters, they do not address all of the needs of municipalities to process certain types of wastewaters. They also fail to address the needs of small municipalities who have relatively small scale applications.